document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1198862>Question 1198862</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Given the following elements of an arithmetic series, a1=3 and a5=-17, find a21.\r<BR>\n" );
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document.write( "The correct answer is one of the following.  Which one is correct?\r<BR>\n" );
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document.write( "A) -51\r<BR>\n" );
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document.write( "B) -100\r<BR>\n" );
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document.write( "C) -97\r<BR>\n" );
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document.write( "D) -92 </SPAN>\n" );
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document.write( "Use the two given numbers in the sequence to find the common difference.<br><BR>\n" );
document.write( "a5 is equal to a1 plus the common difference 5-1=4 times:<br><BR>\n" );
document.write( "-17 = 3 + 4d<BR>\n" );
document.write( "-20 = 4d<BR>\n" );
document.write( "d = -5<br><BR>\n" );
document.write( "Use that common difference and one of the given numbers to find the 21st term.<br><BR>\n" );
document.write( "a21 is equal to a1 plus the common difference 21-1=20 times:<br><BR>\n" );
document.write( "a21 = 3+20(-5) = 3-100 = -97<br><BR>\n" );
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